The invention relates to polymercapto derivatives of polyether condensation polymers which are formed by esterifying, with a mercaptocarboxylic acid, a polyoxyalkylene backbone bearing pendant hydroxymethyl groups. It also relates to curable compositions and to methods for forming cross-linked polymers using said compositions.
Previously, compositions having polymercapto-functionality have been prepared by condensing a mercaptoalkanoic acid with lower polyols such as glycerol, pentaerythritol, ethylene or propylene glycol and the like or with polyhydroxy polyethers generated by such a polyol initiator condensed with an alkylene oxide such as ethylene or propylene oxide; U.S. Pat. No. 2,789,958; 3,549,565.
Such compounds are limited in utility by the fact that the number of mercapto functions available is limited by the functionality of the initiator and because the backbones are of limited variety. In contrast, the instant compounds have relatively unlimited mercapto-functionality due to the controllable nature of the unit (I) below, as well as great flexibility in the polymer backbone to which said mercapto groups are attached. This property makes them especially useful in preparing cross-linked polymeric materials having a wide variety of properties, including variable cure rates and variable solubility due to the varied nature of the polyoxyalkylene backbones of the invention compounds and the variability of the degree of mercapto-functionality.